Electric switch.



T. E. BARNUM..

ELECTRIC SWITCH.

APPLICATION FILED DEC. I5. I9I4.

1,275,200. .PIIIenIedAug.13,1918.

- PATENroFn-Ion Tnoiusn am, onmrnwnuxiin, WISCONSIN, AssmNon 'ro THE comma-minnen ure. co., or MILWAUKEE, WISCONSIN, n CORPORATION or wIseoNsIN.

' Y nancrarcswrrcn.

To all whom it concern Be it known that I, THOMAS Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and cise, and exact description, reference'being had to the accompanying drawing, forminga part of this speciicatlon.y

This invention relates to electric4 switches and more'particularly to those of the pressure operated type.

Such switches* are commonly employed to automatically control suitable apparatus in accordance with predetermined governing pressures and itv is customary to' provide means :for effecting operation of the switch to open or. close circuit .when such pressure rises above a certain' maximum and to close or open circuit when the pressure falls below a certain It is one of the objects of this invention to provide simple and .improved means for varying at will the pressure at which the switch will operate in one direction without affecting the pressure limit at which the.

` the operatlng means therefor,`the extremity hereinafter in connection with a vdescrip-- tion of the accompanying drawing. which illustrates a typical embodiment of theinlas vention, and in which- Figure 1 is a plan v1ew of`an'electric1 tuatlon of the contact member 1n opening switch, and f Fig. 2 is a side view thereof partially 1nl section, and z Fig. 3 is a detail perspective view. Y

yThe pressure operated switch illustrated comprises in general a diaphragm pressure device A arranged to'move a lever 1 for acbetween the parts of theframe b connecting screws 9. Resting upon' said 'aphragm and projecting centrally through the cover E. 13mm," a citizen of the United States, residing at agm 8 of suitable material isdisl is tripped the energy of Patented Aug. 13, 191s.

- application area nebenbei 1 5, 1914. smal No. 877,331.

`-of the pressure chamber is a piston 10 1191*@ mally biased inwardly by a main coil spring l11 confined between the outer end of the piston and a cap plate 12 slidably mounted on spaced uprights 13 and adjustable thereon 'to vary the normal tension of said spring- The upper part of the frame 6 has also an elongated integral .extension 14 on which is mounted a rectangular insulating base 15 y carrying the stationary contact 4 and other current conducting parts of the mechanism. The operated contact member of the switch comprises a metal plate` 16 havin secured thereto a yielding extension 17 fwit the contact tip 3 movable to engage the stationary contact on the insulating base. The plate 16 is provided on opposite sides with oset portions 18 having alined lmife edges 19 seated in notches of two spaced posts 20 secured tothe insulating base 15, said member being retained in position by a coil springA 21 disposed within a slotfin the plate and connecting the end of the latter with the extremity of the lever 1 which also .works in the slot of the contact plate. Said lever-land spring 21 inv addition to holdingl the contact member in place also constitute of said lever being movable to carry the pla-ne oftension of said spring across the axis ofv the operated member and thereby effect pivotal movement of the latter, as

`will appear.

'In order to insure an effective snap' accircuit, there is provided a latch 22 pivote to a fixed post 23and projecting through the contact. plate. Said latch is biased b .a

spring 24 to engage and hold the plate w en moved the spring 21 across the axis of the contact plate Ito thereby exert its :force toward voscillating said contact to open cirwhen the latch e coil spring 21 is suddenly released and insures a quick movementv of the operated lever. It is to be noted also that the snap movement of the cuit position. Accordingly;l

This operation, however, is

mechanism is set to open and close circuit.v

head of the pin 31 is biased to extend operated lever does -not occur in either direction until after the operating lever has moved through a major portion of its travel.

The switch operating lever is preferably formed in two sect-ions 27 and27a fixed together by bolts 28 but insulated from each other by suitable washers 29. The lever is pivotally mounted upon an upstanding lug 30 ofthe frame 6 and. is also pivotally hooked over a'spindle extendingv through the pressure piston 10, so that as pressure in the chamber 7 rises above a predetermined point and the piston is moved outwardly the free extremity. of said lever is rocked inwardly and e'ects opening of the switch as described.

As above mentioned, the degree of compression of the main spring l1 may be adjusted at will by the sliding cap 12 to vary equally the pressure limits at which the Further means are provided to vary the pressure limit at which the switch is set to open circuit independently of and without affecting the preselected pressure limit at which the switch will close circuit. llt will thus be observed that the range between the pressure limits at which the switch will operate, may be increased or' di minished at will. In the form shown, the means to vary a single pressure limit comprises a pin 31 loosely journaled throughv the elongated extension 14C of the supporting frame and disposed in the path of movement of an integral lug 32 of the operating lever when the latter is moved in Aresponse to increased pressure in the chamber 7. Said pin 3l is biased outwardly by a coil spring 33 and carries at its lower end a fixed collar 34 which abuts the frame and accordingly maintains the pin head in a denite normal position. The spring 33 is confined between a shoulder 35 at the head of the pin and a loose plate 36 having lateral extensions 37 through which two adjustable screws 38 are threaded to rest in bearings 39 on the supporting frame. By adjustment of said screws it will be apparent that the plat'e 36 may be raised or lowered at will to thereby increase or diminish the normal compression or tension of the spring 33. 1n practice the lower extremity of the screws 38 are beveled and the bearings thereof provided with ll-shaped recesses to receive the same so that the bev-V eled tips of .Said screws rest against the sides of the recesses and are thus yieldably locked against rotation. The outer end of the pin 31 is preferably recessed and a coil spring 40 disposed therein and conlined between the bottom of said recess and the lug 32 of the operating lever, said spring being sub-l servient tothe load spring 33 and accord ingly ined'ective to move the pin 31 downwardly but of sufficient strength to maintain the hooked extremity of the operating lever 27 held against its pivotal axis on the portion 10 and take up any lost motion in the bearings.

1t is to be understood that the total travel of the operating member from opposite exa treme positions to its positions at which the snap actuations of the operated member occur is greater than the distance between said extreme positions. There is accordingly an intermediate neutral travel range of the operating member in which the position of the operated member depends upon the direction from which the operat-ing member is proceeding, z'. e., if the operating member is moving away from its travel limit with th'e switch closed, the switch will remain closed untilsaid operating member reaches a position -where the switch .would be open if said'member were moving from its opposite travel limit. The

Within this neutral travel range of the lug 32 on the operating lever. Accordingly when the switch is operating to open circuit, said lug-132 strikes said pin prior to tripping of the latch 22 and therefore prior to snap movement of the 'contact plate. Thus thespring 33 acts to oppose movement of the switch in opening. 1n closing, however, said lug moves out of engagement with the head of the pin before the operating lever is moved to carry the plane of tension of the coil spring 21 across the axis of the operated contact lever. Thus in closing circuit the coil spring 33 and pin 31 biased thereby neither oppose nor assist the main spring 11. compression of the spring 33 through the plate 36 and screws 38 as described, the pressure limit at which the switch is set to open circuit may be varied at will without affecting in any degree the preselected pressure vlimit at which the spring is setto close lcircuit and without varying the travel of the operating member requisite to effect either operation. For example, assuming the main coil spring 11 to be adjusted so that the switch is set to open circuit when the pressure in the chamber 7 rises to eighty pounds and to close circuit when said pressure falls to sixty pounds, it is apparent by increas ing the tension of the load spring 33 the opening pressure limit of the switch may be increased, :tor example, to ninety pounds while closing pressure limit of the switch still remains at sixty pounds. The main spring 11 may of course be also regulated independently of the load spring to vary equally the opening and closing pressure Accordingly, by varying the' compressed to a greater degree the opening pressure limit of the switch may be increased to one hundredV pounds but with an attendant equal increase of the closing pressure limit to eighty pounds. A further adjustment of the mechanism may be effected 'by the tripping screw 26 on the operating lever. This adjustment, however, variesthe travel of the operating lever required to trip the latch 22 for releasing the contact lever.

It may be noted that the structure as a whole is compact, sturdy and reliable. vThe various parts of the mechanism to which access may be desired, that is, thev terminal connections, the adjustingy means of the mainspring l1 and load spring 33, and the movmg elements of the switch, are all ar- 'ranged on the free side of the device.

What I claim as new and desire to secure by Letters Patent is:-

1. In a pressure responsive switch, in combination, coperating contacts, a Huid pressure device, a member actuated by. said device, an operative connection between -said member and one of said contacts for effecting engagement and disengagement vof said contacts upon movement of said member to predetermined critical positions, and c pressure devicc, aymember actuated by said device, an operative connection between said member and one of said contacts foreffecting engagement and disengagement of said contacts upon reverse movements of said member to predeterminedV critical positions and Separate means acting directly upon said member and opposing movement thereof from one of its critical positions toward the other to reduce its sensitiveness of response to said device, said member being free from inuence by said means during final return movement to saidv former critical position.

' 3. In a` pressure responsive switch, in combination, a switch including a'pivoted contact member, a fluid pressurepdevice, an operating member actuated by said device, a spring connecting said operating member and said contact member whereby theformer upon reverse movements to predetermined critical positions actuates the latter" in opposite directions and a spring pressed device acting directly upon said 'operating member and opposing movement of the same from one of its vcritical positions tow-ard the other to reduce its sensitiveness of response to said fluid `pressure device, said spring pressed device being adjustable to vary such reduction in sensitiveness and being arranged to free said operating member from its influence during final return movement thereof to said former critical position.

,4. In a pressure actuated switch, in combination, anelongated frame, .a switch including a pivoted contact member mounted at one end thereof, a pressure responsive device mounted on the other end of 'said frame, anelongated operating member pivoted to said frame and having one end operatively connected to said device, an energy storing connection between said contact member and -the free end of said switch operating member for effecting a delayed movement of the former in response to vmovement of the latter, .a pivoted latch biased to automatically engage and lock said Contact member in closed position, said -latch being tripped by said operating member during movement thereof into one of its eXtreme positlons, and a sprlng pressed device carried by sald .frame and arranged to oppose movement ofsaid operating memv ber toward said eXtreme position to reduce the sensitiveness of response of said operating member to said device, said spring pressed device being adjust-able to vary such vreduction in sensitiveness and being arranged to act on said operating member only after the same has moved through a part of its range.

lIn witness whereof, I have hereunto subscribed my name inthe presence of two witnesses.' v

i THOMAS E. BARNUM. Witnesses: Y i

v -ARTHUR-SIMON,

C. T. EVANS. 

